Endoscopic mucosal resection device with conductive tissue stop

ABSTRACT

A medical apparatus and method useful for resecting tissue from the gastrointestinal tract are disclosed. The apparatus can include an RF tissue cutting device disposed inward of a side opening in the device. A tissue stop can be used to control the depth of tissue resected, and the tissue stop can include holes for communicating vacuum for drawing tissue into the side opening. The tissue stop can be electrically grounded with respect to the RF tissue cutting device, and the tissue stop can provide one pole of an RF electrical circuit.

FIELD OF THE INVENTION

The present invention is related generally to endoscopy and moreparticularly to endoscopic mucosal resection.

BACKGROUND OF THE INVENTION

Cancerous or benign lesions of the GI tract often start in the mucosallayer of the stomach or intestines. With improved diagnostics andscreening, such lesions are being identified prior to extension into thewall of the stomach or intestines. Unfortunately, definitive therapy hashistorically involved invasive surgical resection of the lesion andadjacent bowel. Treatment of such early lesions by local excision of themucosal, with access via natural orifices, would represent a far lessinvasive approach.

Existing approaches to local mucosal resection have utilized a varietyof endoscopic instruments. Current methods can be described as “suck andcut” or “lift and cut”. In the suck and cut method, a chamber attachedto the end of the endoscope is placed near the lesion, suction isapplied to draw the lesion into the chamber, an electrosurgical snarewithin the chamber is then activated to excise the entrapped tissue.This is done repeatedly to completely resect the affected tissue. In thelift and cut method, a two-channel endoscope is used. Through onechannel of the endoscope a grasper is passed to lift the lesion. Anelectrosurgical snare, passed through the other endoscope channel isplaced around the shaft of the grasper and advanced to encircle thelifted tissue. The snare is then activated to excise the tissue. Bothapproaches are commonly preceded by injecting saline or other solutionsunder the mucosal to raise the lesion away from the underlying musclewall in an effort to limit perforation. This lesion, common in the art,is known as a “bleb”.

UK Patent Application GB 2365340A to Appleyard and Swain discloses atissue resection device for removing tissue with a cavity of variablevolume, which patent application is incorporated herein by reference.

Other devices and methods have been proposed for providing resection oftissue. Still, scientists and engineers continue to seek improvedmethods for the resection of tissue in the gastro-intestinal tract.

SUMMARY OF THE INVENTION

The present invention provides an apparatus which can employ suction toengage mucosal tissue for resection. In contrast to some existingdevices which use suction for endoscopic mucosal resection, the suctionchamber of the present device can open laterally, or on the side ofapparatus corresponding to the long axis of the endoscope. Accordingly,the present invention can employ a suction opening which extendsgenerally parallel to the long axis of the endoscope. Existing deviceswhich employ an opening which is at the distal end of the device havethe plane of the suction opening being substantially perpendicular tothe long axis of the endoscope.

Once tissue is drawn into the resection chamber, an electrosurgical wirecan be used for transection. In contrast to the flexible electrosurgicalsnares used in existing devices, the present invention can employ arelatively rigid wire positioned within the device to be drawn across orpushed across the chamber opeing to excise the entrapped tissue. Thewire is only electrically active over the portion, which is exposed, noninsulated, to the chamber opening. The present invention can alsoinclude a flexible, electrically conductive tissue stop, which canfunction to limit the depth of tissue that can enter the suction chamberfor resection. Such a tissue stop can provide for greater safety ofresection by reducing risk of alimentary canal perforation and reducingpatient burns from monopolar ground pads. The tissue stop can also beperforated for communicating vacuum.

In one embodiment, the present invention provides a medical apparatuscomprising a body with an outer surface having a side opening, the sideopening for receiving tissue therethrough; a cutter adapted to receiveenergy for cutting tissue, the cutter disposed inward of the opening andadapted to traverse a length of the side opening for cutting tissueextending through the side opening; and a tissue stop disposed inward ofthe side opening and the cutter, the tissue stop having at least oneopening therethrough for conveying vacuum to draw tissue through theside opening. The tissue stop can comprise a plurality of openingstherethrough for conveying vacuum.

In another embodiment, the present invention provides a methodcomprising the steps of providing a source of vacuum; positioning aperforated tissue stop in the gastro-intestinal tract; drawing tissueagainst the perforated tissue stop in the gastro-intesinal tract; andcutting a tissue sample from the tissue drawn against the perforatedtissue stop.

In another embodiment, the present invention provides a medicalapparatus comprising: an overtube for receiving an endoscope therein,the overtube comprising a side opening for receiving tissuetherethrough; and a tissue sample device disposed in the overtube, thetissue sample device comprising a tissue cutter adapted to traverse alength of the side opening for severing a tissue sample from tissueextending into the side opening.

In another embodiment, the present invention provides a method forobtaining a tissue sample comprising: providing an endoscope; providingan overtube having a side opening and a tissue cutter; inserting theovertube into a patient's body with the endoscope; receiving tissue intothe side opening of the overtube; and cutting tissue extending into theside opening with the tissue cutter.

In another embodiment, the present invention provides a medicalapparatus comprising: an outer surface having a side opening, the sideopening for receiving tissue therethrough; a cutter adapted to receiveRF energy for cutting tissue, the cutter supported inward of the sideopening and adapted to traverse a length of the side opening for cuttingtissue extending through the side opening; and a tissue stop disposedinward of the cutter; wherein the tissue stop comprises a pole of the RFcircuit.

In another embodiment, the present invention provides a method ofcutting tissue comprising the steps of: positioning an RF cutting devicein the gastro-intestinal tract of a patient; positioning a tissue stopin the gastro-intestial tract; positioning a tissue mass against thetissue stop; energizing the RF cutting device; grounding the tissuestop; and cutting a tissue sample from the tissue mass.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a cutting device, showing a cuttersupport attached to a distal end of an endoscope, and features internalto the cutter support.

FIG. 2 is a cross-sectioned end view of the cutter support of FIG. 1,taken along section line 16-16, showing a circular embodiment of thecutter support and its internal features.

FIG. 3 is a plan view of an alternative cutting element.

FIG. 4 is a perspective view of an an alternative cutting device,showing a flexible overtube slidable along and rotatable about anendoscope.

FIG. 5 is a cross-sectioned end view of the flexible overtube of FIG. 4,taken along section line 18-18, showing a circular embodiment of thecutter support and its internal features.

FIG. 6 is a cross-sectioned end view similar to FIG. 5, showing internalfeatures in a different position by virtue of a tissue bleb sucked intoan aperture in the overtube.

FIG. 7 is a cross-sectioned top plan view of the cutter support of FIG.1, taken along section line 17-17 of FIG. 2, showing a cutting mechanismextended forward of an aperture in the cutter support.

FIG. 8 is a cross-sectioned side elevation view of the cutter support ofFIG. 1, sectioned through the longitudinal axis thereof, showing aperpendicular view of the features of FIG. 7.

FIG. 9 is a cross-sectioned side elevation view similar to FIG. 8,showing a cutting mechanism retracted rearwardly of the aperture into ashear slot.

FIG. 10 is a cross-sectioned side elevation view similar to FIG. 8, withthe addition of tissue shown adjacent the aperture, and a salinesolution injection needle extended to enter the tissue to form a bleb.

FIG. 11 is a cross-sectioned side elevation view similar to FIG. 10,showing the tissue bleb sucked into the aperture and against a stopplate, and the injection needle retracted.

FIG. 12 is a cross-sectioned side elevation view similar to FIG. 11,showing a cutting element being retracted to cut through a first portionof a bleb, wherein mucosal and sub-mucosal tissue are cut frommuscularis tissue.

FIG. 13 is a cross-sectioned side elevation view similar to FIG. 12,showing completion of cutting while vacuum holds the mucosal andsub-mucosal tissue to the underside of the stop plate.

FIG. 14 is a cross-sectioned side elevation view similar to FIG. 13,showing the removal of the cutter support from the muscularis tissueafter the cut has been completed.

FIG. 15 is a schematic view showing a monopolar arrangement of thepresent invention.

FIG. 16 is a schematic view showing a bipolar arrangement of the presentinvention.

FIG. 17 is a schematic perspective illustration of a device of thepresent invention comprising a tissue stop having a foil conductor withrectangular openings thererin, and showing the tissue stop in anoutwardly bowed, generally arcuate configuration.

FIG. 18 is a schematic perspective illustration of the device of FIG. 17showing the tissue stop deflected to a second configuration, such as byapplication of vacuum, to receive tissue and to permit passage of anendoscope thereby.

FIG. 19 is a schematic illustration an end view of one embodiment of thedevice of the present invention having an overtube that has a flattenedor oval non circular cross-section, and depicting a tissue stop plate infirst and second configurations, with the second configuration shown inphantom.

FIG. 20 is a schematic illustration of an embodiment of the device ofthe present invention including a transparent overtube, a transparentsleeve, and a perforated stop plate.

FIG. 21 is a schematic illustration of an embodiment of the device ofthe present invention including a tissue receiving aperture havingserrated side edges.

FIGS. 22A-22F illustrate various wire cutter configurations.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 1, 2, 7 & 8, one embodiment of a cutting device20 of the present invention is shown attached to a distal end 22 of acommercially available endoscope. Endoscope 24 may be made by OlympusOptical, having an outside diameter of about 0.2 to 0.7 inches. Cuttingdevice 20 can have a rigid or semi-rigid cylindrical cutter support 26which is attached to the endoscope perimeter by any suitable means, suchas by shrink wrap, adhesive, snap fit, press fit, threaded engagement,or other suitable means known in the art for connecting one generallyhollow member to another along parallel longitudinal axes.

Distal end 22 of endoscope 24 can be located at one end of cuttersupport 26. A flexible conical member 28 can be attached to theopposite, distal end of cutter support 26. Conical member 28 can beemployed to provide for a smooth entry of cutting device 20 into thealimentary canal of a patient. Conical member 28 can have an open distalend 30 of about 0.3 inches in diameter through which tooling, not shown,from a working channel 32 of endoscope 24 may extend, and through whichunobstructed camera vision of the inside of the patient's alimentarycanal is obtained. Conical member 28 can have an open distal end 30which permits passage of the distal end of the endoscope 24therethrough.

Conical member 28 can be made of a flexible polymer, such aspolyvinylchloride (PVC), polyethylene terephthalate (PET), or othersuitable flexible materials. Conical member 28 can be attached to cuttersupport 26 by threading it thereon, polymer welding, press fit,snap-fit, or other means well known in the art. Conical member 28 can becoaxial with cutter support 26, whereas a longitudinal axis of endoscope24 can be offset from a longitudinal axis of cutter support 26.

Cutter support 26 can be generally cylindrical in shape, and can have anouter diameter of between about 0.50 and 0.75 inch, and an axial lengthof between about 1.0 and about 1.50 inch. In one embodiment, cuttersupport 26 can have an outer diameter of about 0.60 inches and an axiallength of about 1.25 inches. Cutter support 26 can be formed of atransparent polymer, such as polycarbonate or PVC.

Cutter Support 26 also can employ a lateral tissue receiving aperture34. Aperture 34 can have any suitable shape, and in the embodiment shownis generally rectangular when viewed straight on, and is positionedalong one side of the cutter support 26. The lateral tissue receivingaperture 34 can be about 0.60 to 1.00 inches long (as measured parallelto the axial length of the cutter support 26), and about 0.30 to 0.50inches wide (as measured around the circumference of the outside surfaceof the cutter support 26).

A perforated tissue stop plate 36 can be disposed radially inward fromtissue receiving aperture 34, to be positioned inward of tissuereceiving aperture 34. Tissue stop plate 36 can be injection molded tothe inner wall of cutter support 26, or alternatively, made separatelyand otherwise fixedly attached to the inner wall of cutter support 26.Stop plate 36 can be semi-rigid, and can be deformable. In oneembodiment, stop plate 36 can be formed and attached to cutter support26 so that stop plate 36 can take on a first configuration (such as anoutwardly bowed, generally arcuate configuration), and a secondconfiguration at least a portion of the tissue stop plate is drawn orotherwise deformed or deflected inward (such as by vacuum) to receivetissue through the aperture 34. Stop plate 36 can be, in whole or inpart, transparent, and can be made of or comprise a conductive material.For instance, stop plate 36 can be formed of a polymer or biocompatiblemetal which is conductive, or a polymer having a conductive ink appliedthereto, or can include a generally transparent base layer with aconductive outer layer having openings therethrough, such as in the formof a grid pattern.

In FIG. 1, stop plate 36 is shown having a plurality of perforationstherethrough. Perforations in stop plate 36 can be employed to provideopenings through the thickness of the stop plate 36, and to communicatevacuum from a source of vacuum to draw tissue into the tissue receivingaperture 34. In one embodiment, the perforations in the stop plate 36can be about 0.03 to 0.10 inches in diameter and spaced about 0.10 to0.30 inches apart. While circular perforations are shown, other suitableshapes, including rectangular, square, elliptical, or oval shapes can beemployed.

Cutter support 26 can have a support 38 molded therein, which containsrectangular wire guide slots 40 (FIG. 2) which can be located parallelto the long edges of aperture 34 on opposite sides of aperture 34. Guideslots 40 can be disposed outward of stop plate 36, and inward ofaperture 34. Wire guide slots 40 are sized for wire insulating sleeves42 to slide longitudinally therein. Insulating sleeves 42 surround twowires that extend from a heating source to distal ends of slots 40 nearconical member 28, where they are attached to a heatable (such as by RFenergy) cutting element 44. Cutting element 44 extends from the sleeves42 across aperture 34. As the wires and sleeves 42 are moved parallel tothe longitudinal axis of cutter support 26 within slots 40, cuttingelement 44 passes across aperture 34 and cuts tissue drawn into aperture34.

Cutting element 44 can be in the form of a straight wire filament about0.01 to about 0.04 inches diameter, a flat blade about 0.01 inches thickand 0.03 inches deep, a braided wire about 0.01 to about 0.04 inches indiameter, or other suitable tissue cutting devices. Such cutting elementconfigurations can be about 0.50 inches wide to in order to spanaperture 34, and can be made of a material capable of being heated, suchas by radio frequency (RF) energy. Suitable materials from which cuttingelement 44 can be formed when used with RF energy include electricallyconductive materials including without limitation, steel, steel alloys,titanium, or titanium alloys.

Cutting element 44 may be heated by a number of heating means includingconduction and RF heating, which are commonly known in the endoscopiccutting art. Wire sleeves 42 can be formed of electrical insulatingmaterial such as teflon and can be about 0.03 inches in diameter.Electrically conducting wires and their sleeves 42 can extend along theoutside of endoscope 24 to an insulated slide block 46. Block 46 can beis slidably attached to a handle located alongsidean endoscope operatinghandle. Sleeves 42 can be slidably attached at multiple places toendoscope 24 along its length. Slide block 46 can be supported to movelongitudinally according to arrow 47 in FIG. 1, to extend and retractsleeves 42 along endoscope 24 and through wire guide slots 40 so thatcutting element 44 may be moved past the entire length of aperture 34.Moving block 46 in a distal direction moves cutting element 44 acrossthe length of aperture 34 in a distal direction, while moving block 46in a proximal direction moves cutting element across the length ofaperture 34 in a proximal direction.

For RF heating embodiments, an RF generator can be connected to thewires attached to the cutting element via a switching mechanism todeliver a wattage range of from about 10 to about 150 watts at asuitable frequency, such as a frequency of between about 300 kiloHertzto 3 megaHertz, thereby rapidly heating cutting element 44 to atemperature from about 60° C. to about 120° C. whenever heating isdesired. In one embodiment, an Erbe 300 brand generator can be used withthe following settings in monopolar or bipolar mode: pure cut, 40 Watts.

In an RF heating embodiment an RF grounding plate or pad is typicallylocated outside a patient's body. However, in the present invention anRF grounding plate may be located within cutting device 20, for example,by forming tissue stop plate 36 of a conducting material, or disposing aconductor on using tissue stop plate 36 as a metal or metallizedelectrical grounding plane. FIG. 2 shows an attachment of a ground wire48 to the edge of stop plate 36. Ground wire 48 extends along sideendoscope 24 to a ground, not shown, attached to the RF generator.Accordingly, the cutting device 20 can provide an electricalconfiguration which cutting element 44 provides one pole, and the tissuestop plate 36 provides the other pole.

Support 38 for wire slots 40 can also include at one or both ends of thewire slots a cutting element shear slot 50, into which cutting element44 moves at the end of a cutting stroke in order to strip tissue fromthe cutting element. With shear slots 50 located at both ends ofaperture 34 (as illustrated in FIG. 7), cutting may occur in eitherdirection, pushing or pulling cutting element 44 through tissue. Thesizes of shear slot 50 and cutting element 44 can be selected such thatany removed tissue will not be allowed to adhere to the cutting element44 due to the wiping action of the elements. For example, a cuttingelement 44 having a diameter of about 0.020 inch and fitting within ashear slot 50 with a clearance spacing of about 0.005 inch is suitable.

FIG. 3 shows one of many possible configurations of an alternativecutting element 52, which includes a pointed portion 54. One or morepoints may be employed to “bite into” or initiate contact with tissueand begin cutting without deflecting the tissue out of the path of thecutting element. Also, an angled or pointed cutting element allows forslicing tissue parallel to aperture 34 in a progressive fashion toreduce resistance of cutting. Cutting element 44 may also have amodified surface to be roughened or otherwise textured such as by beingsand blasted, bead blasted, and/or machined roughened, which roughenedprofile can be useful to improve cutting efficiency by biting into thetissue to be resected.

FIGS. 22A-22F show various wire cutter configurations. FIG. 22Aillustrates a rectangular wire for providing intial cutting across thefull width of the wire. FIG. 22B illustrates an angled cutting wire forinitiating cutting at one corner of the wire, and for progressivelyengaging more tissue as the cutting wire is advanced along the length ofthe aperture 34. FIG. 22C illustrates a multiple point wire forproviding multiple points of contact with tissue. FIG. 22D illustrates asingle point or notch for providing single point contact upon initialtissue engagement. FIG. 22E illustrates a relatively sharp single pointcutter for relatively high initial current density and mechanicalpenetration. FIG. 22F illustrates a wire cutter having a flattened (asopposed to circular cross-section) blade which can have a sharpened edgeand points for cutting tissue with or without RF energy.

Serrated edges can provided along the perimeter of a tissue receivingaperture. The textured surface provided by serrated aperture edges canprovide for better gripping of the tissue during cutting. FIG. 21illustrates a tissue receiving aperture having serrated edges.

In order to cut a mucosal layer of tissue from the alimentary canal of apatient for external study, the mucosal layer and sub-mucosal layers aretypically separated somewhat from a muscularis layer of tissue byinjecting a saline solution between them. This is commonly done byextending an injection needle through working channel 32 of endoscope 24to contact and penetrate the target tissue.

In one embodiment, the present invention can provide an improved deviceand method for injecting saline solution. In the embodiments shown inFIGS. 1, 2, and 7-14, support 38 has secured therein a flexible sheath56 for an injection needle 58. Sheath 56 can extend along side endoscope24 to a handle, not shown, which is operated to deliver saline solutionthru a hollow cable connected to injection needle 58. The hollow cablecan be slidable within sheath 56 so that needle 58 may be extendedbeyond the fixed end of sheath 56 to engage mucosal tissue adjacentaperture 34. Sheath 56, which can be fixedly attached to cutter support26, serves as a needle guide that is supported on the cutter support 26.Sheath 56 can enable the operator of the injection needle to control itsposition more accurately (in order to avoid penetrating the muscularistissue) than when a needle and a sheath are operated through anendoscope's working channel.

Injection needle 58 can be used to deliver saline solution 60, as shownin FIGS. 10-13, through mucosal tissue 62 and sub-mucosal tissue 64only. These softer tissues separate from stiffer muscularis tissue 66when saline solution 60 is introduced. After injection, the needle iswithdrawn from the tissue. Needle 58 and sheath 56 are shown in FIG. 2in a retracted position extending through support 38 and angled towardaperture 34, in a plane which generally bisects aperture 34 and iscentered between wire slots 40.

Tissue is drawn into aperture 34 by means of vacuum from a vacuumsource, not shown, external to the patient's body. A suitable vacuumsource can provide a vacuum of about 50 to 250 mm hg. Vacuum can bedrawn through working channel 32 in endoscope 24. Air is drawn from thepatient's alimentary canal, causing the canal to close down aroundcutter support 26 and bring tissue layer 62 in contact with the side ofcutter support 26 where the tissue engages aperture 34. Vacuumcommunicated through the working channel 32 of the endoscope 24 and thenthrough the openings in the stop plate 36 draws tissue layer 62 againststop plate 36 as air flows through the openings in the stop plate 36 tothe opposite side of stop plate 36 where the distal end 22 of endoscope24 can be positioned.

Although FIG. 2 shows a circular cross-section for cutter support 26, aflattened oval or other shape may enable an aperture to be wider forcutting a larger sample of tissue. Similarly, while aperture 34 is shownas a generally rectangular shaped opening on a cylindrical surface,other aperture shapes can be employed, including without limitationoval, circular, and polygonal.

FIGS. 4-6 illustrates an alternative embodiment of a cutting device 80of the present invention. In FIGS. 4-6, an endoscope is not fixedlyattached to a cutting device 80. Instead, the cutting device 80 cancomprise an overtube 86. The overtube can slide along an endoscope androtate about the endoscope. Such an embodiment can permit closer accessby the distal end of the endoscope to target tissue for examinationand/or manipulation before or after mucosal tissue cutting.Alternatively, the cutting device and overtube can employ integralvacuum lines and visualization means (e.g. ccd camera) so that thecutting device and overtube can be used independently of an endoscope.

In FIG. 4, cutting device 80 is shown having a distal end 82 of acommercially available endoscope 84 extended therethrough. Endoscope 24may be made by Olympus Optical, having an outside diameter of about 0.2to 0.7 inches. Cutting device 80 has a flexible cylindrical overtube 86slidably disposed along the length of the endoscope perimeter alongparallel longitudinal axes. Overtube 86 can be relatively short andrigid, or can be flexible enough to conform to the articulations offlexible endoscope 84. Overtube 86 can have has at a distal end aflexible conical member 88, which provides for a smooth entry of cuttingdevice 80 into the alimentary canal of a patient. Conical member 88 canbe made of a flexible polymer such as PVC, PET, etc., and it has an openouter end 90 about 0.3 inches in diameter. The opening in the outer endcan expand or be enlarged upon application of force so that endoscope 84may extend therethrough. Conical member 88 can also be made of flexiblepolymer, and can be integral with overtube 86, or attached to overtube86, such as by threading it onto overtube 86, by polymer welding, bysnap-fit, or by other means. Conical member 88 cab be coaxial withovertube 86, whereas a longitudinal axis of endoscope 84 may be offsetfrom a longitudinal axis of overtube 86, as shown in FIG. 2. Theflexibility of the conical member 88 allows distal advancement of theendoscope to deflect the open end so that the endoscope is able to passthrough the open end of member 88.

Overtube 86 can have a smooth outer diameter of about 0.40 to about 0.80inches and a length of about 0.7 to 2.0 inches. The overtube 86 can bedisposed at the distal end of a elongated, flexible tube or sleeve. InFIG. 4, the proximal end of the overtube 86 is molded or otherwiseconnected a flexible sleeve for receiving an endoscopic therethrough,which sleeve can be in the form of an elongated, corrugated tubularportion 92. Alternatively, the tubular portion 92 can be generallysmooth. Tubular portion 92 can have an internal diameter sized toreceive an endoscope therethrough, and tubular portion 92 can have alength at least about the length of the portion of the endoscope whichis inserted into the patient. Corrugated portion 92 can have generallythe same outside diameter as overtube 86. It may be connected to theovertube similar to the conical member, and shrink wrap material may beadded at the connection to seal the corrugated portion to the overtube.In one embodiment, the flexible, elongated corrugated portion 92 canhave a length of between about 2.7 feet and about 4.0 feet. In oneembodiment, the internal diameter of the tubular portion 92 can begreater than 0.15 inch and less than about 0.85 inch, and moreparticularly between about 0.30 to about 0.75 inch.

Overtube 86 has a rectangular tissue receiving aperture 94 along oneside, which is about 0.80 inches long and about 0.40 inches wide. Aflexible stop plate 96 can be disposed just inside aperture 94. Stopplate 96 can be fastened to the inner wall of overtube 86 or otherwisedisposed in aperture 94 such that stop plate 96 is able to togglebetween (or otherwise assume) two different configurations. Two oppositeedges of the stop plate 96 can be joined directly or indirectly alongtheir lengths to the overtube 86, while the two opposite end edges ofthe stop plate can remain free and unconnected to other portions of thedevice to facilitate movement of the stop plate from one configurationto another. In one embodiment Stop plate 96 can have a width greaterthan a chord length across the overtube where stop plate 96 is mountedso that stop plate 96 is bowed (or otherwise deflected or deformed) in agenerally arcuate fashion toward aperture 94 or away from aperture 94.In one embodiment, the flexible stop plate 96 is biased to bow towardaperture 94 to enable endoscope 84 to pass over it on an opposite side.In such an embodiment, stop plate 96 can be formed of a thin flexiblematerial, such as PVC, PET or other flexible polymer. Stop plate 96 canhave a thickness of less than about 0.05 inches, and can extendlongitudinally beyond both ends of aperture 94.

The outwardly facing surface of stop plate 96 can include a portionwhich is conductive and which can serve as a ground or other pole of aelectrical cutting circuit. In one embodiment, stop plate 96 has aconductive ink applied to one surface (e.g. the outwardly facingsurface) so that it may serve as a grounding plate for RF heating of acutting element as described for cutting device 20. Alternatively, anelectrically conductive surface may be co-extruded on the stop plate 96,or the stop plate may be made of thin bio-compatible metal.

Overtube 86 can have a support 98 molded therein, which containsrectangular wire guide slots 100 between stop plate 96 and aperture 94.Wire guide slots 100 are sized for insulating sleeves 102 to slidelongitudinally therein, just outside the width of aperture 94.Insulating sleeves 102 surround two wires that extend from an RF heatingsource (not shown) to distal ends of slots 100 near conical member 88,where they are attached to a heatable cutting element 104. Cuttingelement 104 extends from the sleeves 102 across aperture 94. As wiresand sleeves 102 are slid parallel to the longitudinal axis of overtube86 within slots 100, cutting element 104 passes across aperture 94 inorder to cut tissue of a patient drawn into aperture 94, similar to theoperation of cutting device 20. Cutting element 104 can be the same asthat described for cutting element 44 or cutting element 52 above.

Cutting element 104 may be heated by a number of heating means includingconduction and RF heating, which are commonly known in the endoscopiccutting art. Wire sleeves 102 are made of electrical insulating materialsuch as Teflon, similar to insulating sleeves 42, and they extend alongthe outside of endoscope 84 to an insulated slide block, not shown. Theslide block, similar to slide block 46, can be slidably attached to ahandle located alongside an endoscope operating handle, such that theslide block is moved longitudinally to extend and retract sleeves 102along endoscope 84 and through wire guide slots 100 so that cuttingelement 104 may be moved past the entire length of aperture 94 inovertube 86.

The heating of cutting element 104 may be the same as or similar tocutting element 44. In an RF heating embodiment, an RF grounding surfacemay be located within cutting device 80, for example by using aconductive tissue stop plate 96. Alternatively, a grounding plateseparate from the stop plate 96 can be employed, but outside of the pathof endoscope 84, so that the endoscope may freely pass through theovertube. A ground wire can be attached to the separate ground plate orto the stop plate, and the ground wire extends to a grounded locationoutside of the patient.

Supports 98 can also include, at each end of the wire slots 100, cuttingelement shear slots 110. The cutting element 104 can move into the shearslots 110 at the end of a cutting stroke in order to strip tissue fromthe cutting element. Such shear slots 110 can be the same as or similarto slots 50 of cutting device 20, and cutting may occur in twodirections, either by pushing cutting element distally, or by pullingcutting element 104 proximally, through tissue.

FIGS. 4-6 show that overtube 86 has secured in support 98 a flexiblesheath 116 for an injection needle 118. Sheath 116 extends along sideendoscope 84 inside corrugated portion 92 to deliver saline solutionthru a hollow cable connected to injection needle 58, in a similarmanner to sheath 56 and needle 58, to engage mucosal tissue adjacentaperture 94. Needle 118 and sheath 116 are shown in FIGS. 4 and 5 in aretracted position extending through support 98 and angled towardaperture 94, in a plane centered within aperture 94, and between wireslots 100 and the aperture.

As shown in FIG. 6, when cutting device 80 is slid along endoscope 84 toa position where endoscope 84 no longer interferes with the toggling ofstop plate 96, tissue may be drawn into aperture 94 by means of vacuumfrom a vacuum source, not shown, external to the patient's body. Vacuumis drawn through working channel 112 in endoscope 84. Air is drawn fromthe patient's alimentary canal, causing the canal to close down aroundovertube 86 and bring tissue 114 in contact with the side of overtube 86where the tissue engages aperture 94. Vacuum draws tissue 114 againststop plate 96 and causes stop plate 96 to toggle away from, or otherwisedeflect or deform away from, the aperture 94.

Although FIGS. 5 and 6 show a circular cross-section for overtube 86, aflattened oval or other shape may be used to permit an aperture to bewider for cutting a larger sample of tissue.

Cutting devices 20 and 80 are operated in a similar manner to remove atissue sample. FIGS. 10-14 describe one method of using cutting device20. FIG. 10 shows typical alimentary canal tissue, with mucosal layer 62atop sub-mucosal layer 64 atop muscularis layer 66 brought into contactwith aperture 34, by placement of the cutting device against the tissueor by a low level of vacuum from the endoscope working channel to closethe alimentary canal wall against cutter support 26. In this position,needle 58 is extended from sheath 56 by pushing a hollow cable throughthe sheath, as described hereinbefore. Saline solution 60 is theninjected into the tissue through the needle, preferably at a depth wheresub-mucosal tissue and muscularis are separable, as is commonlyunderstood in the endoscopic mucosal tissue cutting art. An amount ofsolution 60 is injected which separates the layers sufficient forcutting layers 62 and 64 without cutting layer 66.

FIG. 11 shows needle 58 withdrawn from the tissue and a higher level ofvacuum sucking the tissue into aperture 34 and against stop plate 36.Cutting element 44 in this particular method, is shown extended to shearslot 50. RF energy is now delivered via wires surrounded by insulatingsleeves 42 to cutting element 44, using conductive stop plate 36 as aground for the RF energy path. Wire 48 connects stop plate 36 to anexternal ground, not shown. Cutting is ready to begin as cutting element44 is rapidly heated to the desired temperature by controlling the levelof RF energy.

FIG. 12 shows slide block 46 being moved along arrow 120 to pull cuttingelement 44 into tissue layers 62 and 64 and solution 60. Solution 60 canbe drawn out by the vacuum, which vacuum can also be employed to securethe cut portion of tissue layers 62 and 64 against stop plate 36.

FIG. 13 shows slide block 46 being moved further along arrow 120 tocomplete the cut and shear tissue off cutting element 44 by pulling thecutting element into shear slot 50. Severed layers of tissue 62 and 64continue to be held against perforated stop plate 36 by vacuum fromendoscope 24 located on the opposite side of the stop plate. RF powercan then be switched off. In FIGS. 12 and 13, stop plate 36 is not shownas being deformable. However, it will be understood that stop plate 36can be made to be deformable as described above.

FIG. 14 shows cutting device lifted away from the remaining layers oftissue so that the cutting device may be withdrawn from the patient toexamine the cut sample of tissue. A relatively lower level of vacuum canbe employed to hold the cut tissue against the stop plate. The endoscopeand cutting device may be rotated to a position such that the tissuesample is held against the stop plate by gravity when the vacuum isturned off. Alternatively, the cutting element (with not RF powerapplied) can be moved forward to a position similar to that of FIG. 12to hold the cut tissue against the stop plate when the endoscope andtissue support 26 are manipulated to withdraw them from the patient. Inanother alternative, the cut tissue can be released from the stop plateand allowed to exit the aperture. Then the endoscope and cutting devicecan be partially withdrawn to where a gripper may be extended from aworking channel of the endoscope through open distal end 30 to grasp thecut sample of tissue.

FIG. 15 shows a monopolar arrangement of one embodiment of the presentinvention. The electrocautery generator 200 supplies the RF energy via aground connected to the ground pad 203 at the patient's skin. The RFenergy path 205 is connected to the RF cutting element 44/104. Thevacuum pump 201 communicates with the cutter support 26/overtube 86 viaa vacuum channel 204 which can be integral to the endoscope 84

FIG. 16 shows a bipolar arrangement of another embodiment of the presentinvention. The electrocautery generator 200 supplies the RF energy viaenergy paths 205. One polarity of the RF energy path 205 is connected tothe RF cutting element 44/104 and the other polarity is connected to thestop plate 36/96. The vacuum pump 201 is connected to the support26/overtube 86 via a vacuum channel 204 which can be integral to theendoscope 84.

FIGS. 17 and 18 illustrate an emobidment of the present inventionwherein the overtube 86 and elongated portion 92 can be transparent, andwherein the tissue stop plate 96 can be formed of a thin, transparentflexible polymeric material with a conductive grid 97 disposed on asurface of the tissue stop 96 facing the tissue recieiving aperture 94.Grid 97 can define grid openings 99, which are generally rectangular inFIGS. 17 and 18. One or more openings 99 can be perforated forcommunicating vacuum therethrough if desired. Grid 97 can be formed of asuitable conductive material, such as a conductive metallic foil, or bepainted or printed on with a conductive ink or coating. The conductivesurface of the grid 97 can be between about 2 and about 10 times theconductive surface area of the cutter 104, and in one embodiment theconductive surface area of grid 97 can be about 4 times the conductivesurface area of cutter 104.

The tissue stop 96 in FIGS. 17 and 18 can take on a first configurationin FIG. 17 (which permits passage of an endoscope thereby), and a secondconfiguration shown in FIG. 18 when vacuum is applied (such as throughendoscope 84) for limiting the amount of tissue drawn into aperture 94.The longitudinally extending sides 95 of tissue stop 96 can be fixed,such as by being joined to overtube 86. The proximal and distal ends ofthe tissue stop 96 can be unsupported and free to deform. The first andsecond configurations can be bowed, generally arcuate shapes, as shownin FIGS. 17 and 18. In one embodiment, the tissue stop 96 does notstretch or elongate in taking on the first and second configurations,but instead “toggles” or “snaps-through” from one configuration to theother.

A suitable tissue stop 96 can be formed from a section of a clear PETangioplasty balloon. The tissue stop 96 can be an arcuate segment cutfrom a generally cylindrical angioplasty balloon formed of PET. Thearcuate segment can be cut from an angioplasty balloon cylinder having adiameter between about 10 and about 16 mm and a wall thickness of about0.001 to about 0.002 inch. One suitable angioplasty balloon from whichtissue stop 96 can be formed is a 10 mm diameter angioplasty balloonhaving a wall thickness of 0.002 inch (0.05 mm) available from AdvancedPolymers of Salem, N.H. An arcuate segment can be cut from theangioplasty balloon to form the clear tissue stop 96. A thin metallicfoil having a thickness of about 0.005 inch or less, such as a steelfoil having a thickness of about 0.001 inch can then be applied to thesurface of the stop 96 facing tissue receiving aperture 94, such as withan adhesive. Prior to attaching the foil to the stop 96, the foil can becut to form a series of openings therethrough to provide the grid 97shown in FIGS. 17 and 18.

FIG. 19 illustrates a cross-sectional view of an overtube 86 having anoncircular cross-section, with a generally flattened outer surfaceportion in which tissue receiving aperture 94 is formed. An endoscope 84is shown positioned in the overtube 86. The generally flattened outersurface portion is located on a bottom half of the overtube 86 as viewedin FIG. 19. Providing the tissue receiving aperture 94 in such agenerally flattened surface portion can be useful in positioning theaperture 94 relative to tissue to be resected. FIG. 19 also shows firstand second configurations of tissue stop 96, with the secondconfiguration shown in phantom. In one embodiment, the overtube 86 canbe formed in two shell-like halves, such as a generally semi-circularupper half and a non-circular lower half. The tissue stop 96 can beformed from a nonplanar, arcuate section of thin polymeric film material(such as a section of an angioplasty balloon described above), and theside edges of the arcuate tissue stop can be captured between the upperand lower halves of the overtube as the upper and lower halves arejoined together, such as by adhesive or other suitable means. Theproximal and distal ends of the tissue stop 96 can remain free andunsupported so that the tissue stop can snap through, toggle, or otherwise deflect from the first configuration to the second configuration.

FIG. 20 illustrates an embodiment of the present invention having atransparent overtube 86 and transparent elongated sleeve portion 92. Thetissue stop 96 is generally planar, with generally circular shapedvacuum openings therethrough. FIG. 21 illustrates an embodiment of thepresent invention wherein the overtube 86 has a tissue receivingaperture having serrated side edges 93 for assisting in grasping andcutting tissue with the cutting element 104. Tissue stop 96 is omittedfrom FIG. 21 for purposes of clarity in illustrating the side edges ofaperture 94.

While the present invention has been illustrated by description ofseveral embodiments, it is not the intention of the applicant torestrict or limit the spirit and scope of the appended claims to suchdetail. For instance, but without limitation, RF energy has beendescribed as the tissue cutting method in the illustrated embodiments,but it will be understood that other tissue cutting modes, such asultrasonic energy modes, mechanical cutting, and other methods could beemployed in various embodiments of the present invention. Numerous othervariations, changes, and substitutions will occur to those skilled inthe art without departing from the scope of the invention. Moreover, thestructure of each element associated with the present invention can bealternatively described as a means for providing the function performedby the element. Accordingly, it is intended that the invention belimited only by the spirit and scope of the appended claims.

1. A medical apparatus comprising: an outer surface having a side opening, the side opening for receiving tissue therethrough; a cutter adapted to receive RF energy for cutting tissue, the cutter supported inward of the side opening and adapted to traverse a length of the side opening for cutting tissue extending through the side opening; and a tissue stop disposed inward of the cutter; wherein the tissue stop comprises a pole of an RF circuit.
 2. The medical apparatus of claim 1 wherein the tissue stop comprises a ground of an RF circuit.
 3. The medical apparatus of claim 1 wherein the tissue stop is deformable.
 4. The medical apparatus of claim 1 wherein the tissue stop comprises at least one vacuum opening therethrough.
 5. The medical apparatus of claim 1 wherein the medical apparatus comprises a passageway sized to receive an endoscope.
 7. The medical apparatus of claim 1 wherein the medical apparatus comprises a cutting element supported in sliding engagement with slots disposed on opposite sides of the side opening.
 8. The medical apparatus of claim 1 wherein the tissue stop is formed of an electrically conductive material.
 9. The medical apparatus of claim 1 wherein the tissue stop has a conductive material applied to one surface thereof.
 10. A medical apparatus comprising: an outer surface having a side opening, the side opening for receiving tissue therethrough; a cutter adapted to receive RF energy for cutting tissue received through the side opening; and a tissue stop disposed inward of the cutter, wherein the tissue stop comprises a portion of an RF circuit.
 11. The medical apparatus of claim 10, wherein the medical apparatus comprises a passageway sized to receive an endoscope.
 12. The medical apparatus of claim 10 wherein the medial apparatus comprises a distal end opening.
 13. The medical apparatus of claim 10 comprising a flexible sleeve for receiving an endoscope therein.
 14. A method of cutting tissue comprising the steps of: positioning an RF cutting device in the gastro-intestinal tract of a patient; positioning a tissue stop in the gastro-intestial tract; positioning a tissue mass against the tissue stop; energizing the RF cutting device; electrically grounding the tissue stop with respect to the RF cutting device; and cutting a tissue sample from the tissue mass.
 15. The method of claim 14 wherein the step of positioning a tissue mass against the tissue stop comprises providing a source of vacuum, and drawing the tissue mass against the tissue stop.
 16. The method of claim 15 wherein the step of drawing the tissue mass comprises drawing the tissue mass through an opening having length and width.
 17. The method of claim 16 wherein the step of cutting the tissue sample comprises drawing an energized portion of the cutting device across a length of the opening. 